Re: [Tarantool-patches] [PATCH 1/2] swim: add SO_BROADCAST option

[Cyrill Gorcunov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

On Thu, Mar 18, 2021 at 09:47:36PM +0100, Vladislav Shpilevoy wrote:
> Hi! Thanks for the review!
> 
> >> diff --git a/src/lib/swim/swim_io.c b/src/lib/swim/swim_io.c
> >> index c8558c43e..45df36ba4 100644
> >> --- a/src/lib/swim/swim_io.c
> >> +++ b/src/lib/swim/swim_io.c
> >> @@ -512,8 +512,23 @@ static inline void
> >>  swim_complete_send(struct swim_scheduler *scheduler, struct swim_task *task,
> >>  		   ssize_t size)
> >>  {
> >> -	if (size < 0)
> >> -		diag_log();
> >> +	if (size < 0) {
> >> +		bool is_critical = false;
> >> +#if TARGET_OS_DARWIN
> >> +		/*
> >> +		 * On Mac this error happens regularly if SWIM is bound to
> >> +		 * the localhost and tries to broadcast out of the machine. This
> >> +		 * is not critical, because will happen in the tests a lot, and
> >> +		 * in prod it simply should not bind to localhost if there are
> >> +		 * multiple machines in the cluster. Besides, Mac as a platform
> >> +		 * is not supposed to be used in prod.
> >> +		 */
> >> +		struct error *last = diag_last_error(diag_get());
> >> +		is_critical = (last->saved_errno == EADDRNOTAVAIL);
> >> +#endif
> >> +		if (is_critical)
> >> +			diag_log();
> >> +	}
> >>  	if (task->complete != NULL)
> >>  		task->complete(task, scheduler, size);
> > 
> > Vlad, I don't understand. For non-mac users this @is_critical will
> > always be false, maybe we better move the whoe branch to TARGET_OS_DARWIN
> > then? Ie
> > 
> > 	if (size < 0) {
> > 	#if TARGET_OS_DARWIN
> > 		if (is_critical)
> > 			diag_log();
> > 	#endif
> > 	}
> > 
> > or you made it this way to escape unused parameter compiler warning?
> 
> I added the variable on all platforms on purpose. Because if the code would
> be done the way you propose above, non-Mac platforms won't log anything.

The do not log anything with the patch. Lets drop TARGET_OS_DARWIN path
from your patch and we will have

swim_complete_send(struct swim_scheduler *scheduler, struct swim_task *task,
                  ssize_t size)
{
	if (size < 0) {
               bool is_critical = false;
               if (is_critical)
                       diag_log();
	}
}

The is_critical is always false, or there is a typo in the code above.


> I, on the contrary, want to log on all platforms, but not certain errors
> in certain platforms. Only EADDRNOTAVAIL and only on Mac. Everything else
> must be logged. Because the user does not call 'send' directly, and has no
> other way to know there was an error except via the logs.